present invention relates to a pressure sleeve.
More particularly, it relates to a pressure sleeve with a vibration pickup, which has a supporting surface for mounting on a structural element, in particular an internal combustion engine, by amounting member extending through an opening of the pressure sleeve.
Pressure sleeves of the above mentioned general type are known in the art. Such pressure sleeves are used for knock sensors which are described for example in the U.S. Pat. No. 4,906,031 and the German patent document DE-OS 40 24 339. The pressure sleeve has a flat and plane supporting surface which is placed on a structural element for determination of vibrations of the structural elements. Due to the shape and working deficiency of the abutment surface, disturbing resonance can occur which can cause faulty measurements and disturbances in the connected circuit.
The German document DE-Gbm 83 12 524.8 discloses the holding device for oriented mounting of a measuring means. This mounting has a conical foot forming a circular elastic sealing lip. The sealing lips have different inclination angles, so that independently from the inclination on the mounting point, the measuring means arranged in the holding device is horizontally oriented. In this holding device the elastic and therefore easily deformable sealing lips provide a horizontal construction, for each purpose the angle of inclination must be relatively great. A plane placement of the measuring unit on the mounting place is not intended.
Further, the German document DE-Gbm 84 36 486.6 discloses a knock sensor which on the outer circumferential edge of the abutment surface is provided with a small region at a distance from the abutment surface. This outer edge is however used for performing the injection molding process. The pressure sleeve itself abuts approximately its whole surface against the mounting part, so that again disturbing resonance can occur.